Posted on August 24, 2017 at 21:30
I am trying to run an application which captures incoming Y only image data on DCMI interface.
Pixel clk is 5MHz, field rate is 50Hz (PAL video), 8 bit luminance only data and discrete sync signals.
MCU is STM32F767IG and camera device is a TVO5150AM1 decoder.
The problem I am facing here is that DCMI capture rate is not as same as VSYNC signal.
In continues mode, When VSYNC frequency is 50Hz, DCMI captured fieldrate is 40Hz.
I had placed a toggle pin at VsyncEventCallback and FrameEventCallback to detect their rates. Yellow one represents Frame(field)rate while the blue one represents VSYNC frequency.
There are similar issues in snapshot mode which causes a frame to be captured from somewhere other that start of a line.
I have to add that it does not overrun, as no errorcallback is triggered.
DCMI configuration code in continues mode:
oid MX_DCMI_Init(void)
{
hdcmi.Instance = DCMI;
hdcmi.Init.SynchroMode = DCMI_SYNCHRO_HARDWARE;
hdcmi.Init.PCKPolarity = DCMI_PCKPOLARITY_RISING;
hdcmi.Init.VSPolarity = DCMI_VSPOLARITY_HIGH;
hdcmi.Init.HSPolarity = DCMI_HSPOLARITY_LOW;
hdcmi.Init.CaptureRate = DCMI_CR_ALL_FRAME;
hdcmi.Init.ExtendedDataMode = DCMI_EXTEND_DATA_8B;
hdcmi.Init.JPEGMode = DCMI_JPEG_DISABLE;
hdcmi.Init.ByteSelectMode = DCMI_BSM_ALL;
hdcmi.Init.ByteSelectStart = DCMI_OEBS_ODD;
hdcmi.Init.LineSelectMode = DCMI_LSM_ALL;
hdcmi.Init.LineSelectStart = DCMI_OELS_ODD;
if (HAL_DCMI_Init(&hdcmi) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
}
void HAL_DCMI_MspInit(DCMI_HandleTypeDef* dcmiHandle)
{
GPIO_InitTypeDef GPIO_InitStruct;
if(dcmiHandle->Instance==DCMI)
{
/* USER CODE BEGIN DCMI_MspInit 0 */
/* USER CODE END DCMI_MspInit 0 */
/* DCMI clock enable */
__HAL_RCC_DCMI_CLK_ENABLE();
/**DCMI GPIO Configuration
PA4 ------> DCMI_HSYNC
PA6 ------> DCMI_PIXCLK
PC6 ------> DCMI_D0
PC7 ------> DCMI_D1
PC8 ------> DCMI_D2
PC9 ------> DCMI_D3
PC11 ------> DCMI_D4
PD3 ------> DCMI_D5
PG9 ------> DCMI_VSYNC
PI6 ------> DCMI_D6
PI7 ------> DCMI_D7
*/
GPIO_InitStruct.Pin = GPIO_PIN_4|GPIO_PIN_6;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF13_DCMI;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7|GPIO_PIN_8|GPIO_PIN_9
|GPIO_PIN_11;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF13_DCMI;
HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
GPIO_InitStruct.Pin = GPIO_PIN_3;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF13_DCMI;
HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
GPIO_InitStruct.Pin = GPIO_PIN_9;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF13_DCMI;
HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);
GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF13_DCMI;
HAL_GPIO_Init(GPIOI, &GPIO_InitStruct);
/* DCMI DMA Init */
/* DCMI Init */
hdma_dcmi.Instance = DMA2_Stream7;
hdma_dcmi.Init.Channel = DMA_CHANNEL_1;
hdma_dcmi.Init.Direction = DMA_PERIPH_TO_MEMORY;
hdma_dcmi.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_dcmi.Init.MemInc = DMA_MINC_ENABLE;
hdma_dcmi.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;
hdma_dcmi.Init.MemDataAlignment = DMA_MDATAALIGN_WORD;
hdma_dcmi.Init.Mode = DMA_CIRCULAR;
hdma_dcmi.Init.Priority = DMA_PRIORITY_VERY_HIGH;
hdma_dcmi.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
hdma_dcmi.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
hdma_dcmi.Init.MemBurst = DMA_MBURST_INC4;
hdma_dcmi.Init.PeriphBurst = DMA_PBURST_SINGLE;
if (HAL_DMA_Init(&hdma_dcmi) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
__HAL_LINKDMA(dcmiHandle,DMA_Handle,hdma_dcmi);
/* DCMI interrupt Init */
HAL_NVIC_SetPriority(DCMI_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DCMI_IRQn);
/* USER CODE BEGIN DCMI_MspInit 1 */
/* USER CODE END DCMI_MspInit 1 */
}
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